Printing Crack-Free Microporous Structures by Combining Additive Manufacturing with Colloidal Assembly.

Area of Science:

• Materials Science
• Additive Manufacturing
• Colloidal Science

Background:

• High printing resolution and scalability are typically incompatible in additive manufacturing (AM).
• Existing AM processes struggle to achieve both macroscale dimensions and fast printing speeds simultaneously.

Purpose of the Study:

• To demonstrate a novel additive manufacturing approach combining direct writing and colloidal assembly.
• To overcome the incompatibility between high resolution and scalability in AM processes.
• To develop methods for printing uniform, crack-free colloidal coatings and templates.

Main Methods:

• Utilizing direct writing as an additive manufacturing process integrated with colloidal assembly.
• Tailoring printing parameters for polystyrene (PS) microparticle-templates to prevent coffee ring formation.
• Introducing a "comb"-strategy for printing macroscale, crack-free colloidal coatings from low-viscosity suspensions.
• Transforming printed templates into ceramic microporous channels and photonic coatings via atomic layer deposition (ALD) and calcination.

Main Results:

• Achieved uniform single lines and macroscale areas by controlling coffee ring formation.
• Successfully printed macroscale, crack-free colloidal coatings using low-viscosity suspensions.
• Fabricated ceramic microporous channels with promising wicking capabilities.
• Created photonic coatings exhibiting broadband reflection in the near-infrared spectrum.

Conclusions:

• The combination of direct writing and colloidal assembly breaks the resolution-scalability barrier in additive manufacturing.
• The developed methods provide guidelines for printing low-viscosity colloidal suspensions.
• This printing process offers significant advancements for novel applications of colloidal-based printed structures.